Semiconductor electronic devices have internal losses which generate heat in use. When the electronic device is configured for a substantial amount of power, cooling is necessary in order to limit the semiconductor device to a sufficiently low temperature to provide a reasonable life. Power modules containing this type of semiconductor component are traditionally attached to a cold plate. The cold plate may have fins thereon with circulation of fluid therepast. The fluid is usually liquid when greater amounts of heat must be dissipated. As long as there is sufficient power to provide more flow of liquid, such a cooling system is satisfactory.
A commonly used current method for cooling high-density hybrid power modules is by clamping them onto a typical internally finned flow-through cold plate. Characteristics of the thermal interface between the module and the cold plate are dependent on numerous variables such as surface finish and roughness, bolt torque, pressure uniformity, interface material conductivity and consistency, and the type of interface material such as gasket, grease or foil. In addition, thermal expansions and contractions, vibration, shock and handling will often vary the initial parameters and cause performance degradation. Typical finned flowthrough cold plates are constructed of aluminum material for manufacturing reasons. The mismatch in thermal expansion rates between the aluminum cold plate and the module base plate creates additional degradation at the thermal interface.
The dissipated power density of present-day power hybrid modules has reached a nominal 500 watts per square inch at the semiconductor chip. Current package power modules are clamped or bolted with the module base plate against the cold plate. The cold plate may have internal passages for fluid flow and internal fins for increased cold plate-liquid coolant interface area. This structure requires the cold plate of minimum thermal resistance and an interface between the power module base plate and the cold plate also of minimum thermal resistance. Achieving flatness is difficult, and tight bolting causes distortion. Thus, there is need for an improved structure by which the semiconductor devices can be cooled with a minimum amount of coolant power.